Re: weird electrics issue on 156
My Alfa develops the same problem also:
I didn't notice if the rear demister failed but I did notice that:
1) front electric windows failed (rear ones ok),
2) central locking failed (alarm ok), and
3) the Interior light failed.
I cant be 100% sure but I think the fault only occurs when it is damp and/or cold, so may be related to a build up of moisture somewhere.
What I have also noticed is that when it is working ok you can generate a similar fault by unplugging one of the plastic sockets in the door hinge. So it could have something to do with this connection getting damp. I've tried WD40 (today) although no improvement yet.
I'd be interested to know if you (or anyone else out there) has any suggestions.